1. Technical Field
The present invention relates to a dielectric ceramic composition and a multi-layer ceramic capacitor comprising the same.
2. Description of the Related Art
Recently, as a size of display devices such as a liquid crystal display (LCD), a plasma display panel (PDP), or the like, has increased and a speed of a central processing unit (CPU) has increased, a heat generation problem has become severe. Therefore, market needs for an X5R or X7R type multi-layer ceramic capacitor capable of securing stable capacitance and reliability at a high temperature for stable operation of an integrated circuit (IC) has increased.
Further, in accordance with the general trends toward miniaturization, lightness, and multi-functionality of electronic products, a multi-layer ceramic capacitor (MLCC) chip product having a small size, high capacitance, and high pressure has continuously been demanded. Therefore, excellent withstand voltage and DC-bias characteristics in addition to thinness of a dielectric layer have been importantly considered in developing the X5R or X7R type multi-layer ceramic capacitor.
The thinness and high pressure increases an intensity of electric field applied to the dielectric layer to deteriorate the DC-bias and withstand voltage characteristics. Particularly, a fine structural defect due to the thinness may have a severe negative influence on the withstand voltage characteristics such as breakdown voltage (BVD), high temperature insulation resistance (IR), and the like.
In order to prevent the negative influence, base material powder should be essentially atomized. However, when a grain size of the base material is decreased, it is more difficult to implement capacitance temperature characteristics, and permittivity may be decreased. Therefore, it is difficult to develop a dielectric raw material.
In order to solve this problem, selection of a base material, development of an additive composition, a material process such as dispersion, or the like, an internal electrode, a control of a firing process should be comprehensively and multilaterally studied. Particularly, it is very important to select a ceramic composition playing a conclusive role in physical properties of a raw material.
The existing high capacitance dielectric ceramic composition satisfying X5R or X7R characteristics (Electronic Industries Association (EIA) standard) is configured to add rare earth (RE) atoms (hereinafter, referred to as the RE atom), a transition element, and sintering aids to BaTiO3 as a main component.
However, in the existing dielectric composition, since it is difficult to control a reaction and sintering property changed depending on a kind of RE atoms, it is not easy to implement reliability so as to satisfy specifications of a product at the time of changing the kind of RE atoms. In addition, in the existing dielectric composition, as the dielectric layer containing BaTiO3 is thin, since it is difficult to control movement of oxygen vacancy causing deterioration of reliability, it is difficult to implement high permittivity.